Mystery Bird: Hutton's Vireo, Vireo huttoni

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[Mystery bird] Hutton’s Vireo, Vireo huttoni, photographed in Boyce Thompson Arboretum, Superior, AZ. [I will identify this bird for you tomorrow]
Image: Richard Ditch, 2008 [larger view].

Please name at least one field mark that supports your identification.


Rick Wright, Managing Director of WINGS Birding Tours Worldwide, writes:
There’s no question that this is a small bird, is there? If we start at the back, we find a shortish, narrow tail stuck on to a comically pudgy body; the shape and the extensive yellow-green edging on the tail feathers that immediately rule out a vast number of small passerines, including all the parulids. The wing feathers show the same edging, along with two clear, broad wingbars, the upper one mostly concealed by feathers overlapping it from the bird’s back. This photo has many merits, among them the way that it shows just how such gross marks as wingbars are created by the fine details of feather patterns: wingbars are formed by contrastingly colored tips to the secondary coverts, the lower bar by the greater coverts, the upper bar by the median coverts.
In a view as splendid as this one, we can analyze the wing pattern in further and productive detail. The tertials are blackish with bold white edges, the secondaries extensively yellow and the primaries heavily edged grayish-white. The “minor” feathers of the wing are strikingly blackish: the alula (beautifully visible in this image) and the greater coverts. Only a few of the median coverts are visible, and even on those only the tips. The lesser coverts, as so often on passerines, are entirely concealed.
This wing pattern actually allows us to identify the bird without going further. Among the small birds of North America, only Hutton’s Vireo shows two equally well-defined white wingbars bordering the blackish rectangle formed by the greater coverts. On Ruby-crowned Kinglet, otherwise remarkably similar in plumage, the greater coverts are much paler, hardly contrasting with the folded flight feathers, and the lower wingbar is considerably better developed than the upper. The blackest part of the kinglet’s wing is below the lower wingbar, a black patch formed by the contrasting base of the secondaries; on the vireo the blackest part is above that wingbar.
There are some important structural differences, too, that will permit the two species to be distinguished in views worse than this. Notice how fat-headed and neckless this bird is; kinglets are a bit more finely built, their heads obviously narrower than their shoulders. And the bill of a kinglet is much sharper and finer than the absurdly blobby bill protruding from the vireo’s face.
Another useful mark is just barely visible in this photo. Look at the toes of this bird: they are moderately thick, as would be the tarsus if we could see it. The toes and tarsus of a Ruby-crowned Kinglet are oddly slender, the result of the different scaling pattern of the two species’ feet: the vireo’s tarsus is scutellate, covered with the usual overlapping scales; the kinglet’s, though, is booted, with a single long scale extending from the ankle almost to the top of the toes. This difference is also responsible for the pale, translucent color of a kinglet’s foot; the thinness of the tarsus and its translucence are often the most easily seen characters on a tiny greenish bird fluttering high in a tree.
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About GrrlScientist

grrlscientist is the pseudonym of an evolutionary biologist and ornithologist who writes about evolution, ethology, and ecology, especially in birds. After earning a degree in microbiology (thesis focus: virology) and working at the Fred Hutchinson Cancer Research Center in Seattle, she earned her PhD in zoology from the University of Washington in Seattle, where she studied the molecular correlates of testosterone and behaviour in white-crowned sparrows. She then worked a Chapman Postdoctoral Fellow at the American Museum of Natural History in New York City, where she studied the speciation and distribution of lories and other parrots throughout the South Pacific Islands. A discarded scientist, she returned to her roots: writing. Formerly hosted by The Guardian (UK), she now writes about science for Forbes and for the non-profit think tank, the Evolution Institute and she writes podcasts for BirdNote Radio. An avid lifelong birder and aviculturist, she lives with a flock of songbirds and parrots somewhere in Germany.
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0 Responses to Mystery Bird: Hutton's Vireo, Vireo huttoni

  1. Larry says:

    Ruby-crowned Kinglet.It has a sort of blank face with a white eye ring,wing bars,and a litle olive color on the flanks. Nice photo!

  2. Single white wing bar, yellowish wash to the primaries, chunky overall – Ruby-crowned Kinglet.

  3. At first I thought Ruby-crowned Kinglet too, but looking closer, I’m going to call this a Hutton’s Vireo. In the real world, I’d be less-prone to mistaking this bird for the Ruby-crowned Kinglet, since I normally ID Ruby-crowned Kinglets first by voice, and then by their fluttering-at-the-branch-tips foraging behavior. The first time I realized I was looking at a Hutton’s Vireo, not a kinglet, was when I spent several minutes scratching my head over an inappropriately non-kinglet-vocalizing, non-kinglet-fluttering, Ruby-crowned Kinglet (I thought).
    Specific clues in this case are the pale edges of the secondaries reaching all the way to the base, rather than being interrupted before that (per Sibley), and, on careful inspection, a beak that is heavier than a kinglet’s, and has a bit of a hooked tip.
    Interesting lesson on the hazards of birding over the Internet, rather than in the field.

  4. The Ridger says:

    I think it’s a Hutton’s Vireo, too. There’s not quite enough white around the eye for a Kinglet, the throat is kind of scruffy (sorry for the non technical term), and the beak is thicker. But I could be wrong – those birds look a lot alike!

  5. Albatrossity says:

    Hutton’s Vireo. Bill too thick for a kinglet, and the feet seem to be all black (kinglet has yellow soles, at least) and more robust than those of a kinglet. The lack of a black bar on the secondaries and primaries (distal to the white wingbar) clinches it.
    It would be impossible to see much of this in the field, of course. But in the field you would have behavioral and vocal cues, so it all evens out.

  6. Larry Gardella says:

    The head shape, bill shape, shape of the eyering, lack of black between the white wing bar and the pale edging all say Hutton’s Vireo.

  7. Bill says:

    Another vote for the vireo. There appears to be a very pale lore. I agree with the comments regarding voice and behavior. The only way we would have gotten our Hutton’s Vireo in French Joe Canyon, AZ, was using these clues since bird size, similarity, and foliage would have made our success more unlikely.

  8. shonny says:

    I would think Ruby-Crowned Kinglet too as the head-shape seems a bit flat for the vireo.
    Also the range seems to be more likely.

  9. Larry says:

    Wow! I just looked up a Hutton’s Vireo and was shocked at the similarity.-I had no idea there would be a species that could look so much like a RC-Kinglet.I definitely learned something new-and here I was thinking-are these people serious?

  10. Michelle Farazdel says:

    I think Hutton’s Vireo because of the thicker bill.